The present invention relates to a ventilation device with a heat exchanger, and more specifically, to a ventilation device of the type installed in an outer wall of a room.
The increasing importance of energy saving and demand for air exchange, particularly in polluted premises, has created a demand for efficient ventilation devices with heat exchange. Devices are known which involve an interchange operation wherein during one interval of operation one or more heat exchange elements are heated by exhausting room air and this heat is released to ingoing ambient air in a following interval of operation.
Known ventilation devices with reversible fans for simultaneously interchanging suction and exhaust, are not able to provide balance in the air delivery when the air direction is changed, as different pressure losses encountered with different directions create unequal air transport volumes. To achieve air balance during operation of the device, velocity control of the reversible fans is needed. Instantaneous adjustment of differences in pressure loss by controlling the fan velocity requires complicated and expensive equipment, and is difficult to achieve.